Spring device

Abstract

A spring device including a piston slidably disposed in an inner cylinder of a dual inner and outer cylinder with a piston rod secured thereto and extending to the outside of the cylinder through a rod guide closing one end of the inner cylinder, an oil passage formed in the rod guide and connecting an annular chamber between the inner and outer cylinders with the interior of the inner cylinder, and a device for supplying a force on the piston to project the piston rod outwardly, in which a guide member is supported on the piston rod with a coil spring interposed between the guide member and the piston, and the guide member is adapted to contact the rod guide to control the oil flowing through the oil passage when the piston rod moves outward by a predetermined amount.

What is claimed is: 
     
       1. A spring device for controlling the opening or closing speed of a door or a window, comprising: concentric inner and outer cylinders in a horizontal attitude and having an annular space therebetween;   a piston slidably mounted in the inner cylinder and a piston rod secured thereto and extending to the outside of the cylinder, said piston partitioning said inner cylinder into two oil chambers, said piston having a passage therethrough with a check valve therein for allowing flow of oil when the piston is moving in the contracting stroke of the device and blocking flow in the extension stroke of the device;   closure members closing opposite ends of the inner and outer cylinders respectively and having oil passages therein connecting said oil chambers respectively with said annular space;   pressurized gas enclosed in the upper portion of the annular space for applying a force on the piston for projecting the piston rod outwardly of said device;   a guide slidably supported on the piston rod in one oil chamber, said one oil chamber being the oil chamber through which the piston rod extends;   a spring disposed between said piston and said guide for normally locating said guide at a position spaced from the piston;   said guide having a face engaging said closure member in said one oil chamber for closing the oil passage from said one oil chamber when the piston rod moves outwardly a predetermined amount;   said closure member for said one oil chamber having a reduced diameter portion projecting into said one oil chamber and the oil passage for said one oil chamber opening into said one oil chamber through the face of said projection facing the interior of said one oil chamber;   said guide having a diameter less than the inner diameter of said inner cylinder and the guide face being large enough to cover said oil passage opening;   an auxiliary oil passage means for permitting a restricted flow of oil from said one oil chamber to said annular space when said guide engages said closure member, said auxiliary oil passage means having a groove with a cross-sectional area less than that of said oil passage in one of said faces, and said groove radially extending across said face from the position of said oil passage and opening at the outer, radial edge of said face, whereby said oil passage is prevented from being totally blocked by said guide when said guide abuts said projection on said closure member; and   an adjustable valve in the oil passage for the other oil chamber.